DE 35 22 916 A1 describes a turbine set with at least one outer casing and a low-pressure turbine stage with an inner casing coaxial to it and with at least one coaxial high-pressure and/or medium-pressure turbine stage arranged upstream of the low-pressure turbine stage. The shafts of the turbine stages are rigidly connected together to form a shafting. Upstream of the low-pressure turbine stage is an axial bearing for the shafting, that is the starting point of the axial shaft expansion and displacement. The inner casing is connected by means of thrust-transferring connecting rods to the end of an axial adjacent turbine stage casing mounted so that it can move axially, or to a turbine bearing casing. The connecting rods are passed out through a wall in the outer casing through a sealing element that enables limited transverse movement and allows for thermal expansion while at the same time providing a vacuum seal. A turbine bearing located before the low-pressure turbine stage defines a second reference plane that forms the starting point of the axial expansion and displacement of the turbine stage casing mounted on this turbine bearing and of the turbine stage casing connected to it. This causes an axial displacement of the shafting and of the turbine stage casing with practically the same axial expansion and in the same direction. This enables minimum axial play between adjacent rotor blade and stationary blade rims. The thrust transfer by means of the connecting rods takes place in the area of the thrust-transferring turbine bearing. Furthermore, a vacuum-tight passage of the connecting rods is structurally combined with a horizontal claw-bearing mounting of the inner casing of the low-pressure turbine stage, the claw-bearing mounting of the inner casing of the low-pressure turbine stage being horizontally moved by heat. The claw arms of the inner casing extend in a direction parallel to the axis of the shaft and their sliding supporting and guiding faces lie against the supports of the associated bearing casing. The fit of the sliding and guiding faces is realized by sliding and adjusting shims. The connecting rods are mechanically connected to the claw arms in the area of the turbine bearings, in particular a diaphragm seal for a vacuum-proof passage is connected by means of an outer annular flange to an end face of the outer casing of the low-pressure turbine stage and has a vacuum-tight connection to a turbine bearing casing section by means of an inner annular flange. The arrangement of the sealing elements between the seat faces at the outer casing end wall and the bearing casing, i.e. between parts with only a slight relative movement, means that the larger thermal displacements of the inner casing are decoupled from the sealing elements.
DE-AS-1 216 322 describes a steam or gas turbine with several coaxial turbine stages arranged one behind the other, the shafts of which are rigidly connected to each other, with at least one of their casings being axially displaceable and connected to a fixed turbine stage casing or bearing pedestal. The low-pressure casing of the turbine in each case consists of an outer and inner casing. The inner casing of the low-pressure turbine is connected to an adjacent turbine stage casing or bearing pedestal by a rod assembly that passes through the wall of the outer casing so as to form a steam-proof seal and enable movement due to heat. The rod assembly can be a single rod sealed in the outer casing wall by a bellows that flexes axially and radially. The rod assembly can also consist of three rods axially in line and connected to each other by hinged joints, the center one of which can move axially with a sliding fit in a sleeve in the outer casing wall. A rod assembly arrangement of this kind is designed to produce an axial displacement of the casing by means of which the axial play between the rotor and the casing is held as constant as possible. To change the magnitude of the axial play, it is possible to change the length of the rod assembly by changing its temperature. This change in temperature is brought about by an additional heat load on the rod assembly by means of steam or a liquid.
A change of this kind in the magnitude of the axial play, whereby hot steam is carried in a tube is described in GB-PS-1,145,612. An axially-expandable tube is connected to a rod at each of its end faces that in turn is secured to the inner casing of a low-pressure turbine stage. An axial displacement of the inner casing relative to a turbine rotor consists in each case of the particular expansion of the inner casing, the expansion of the connecting rods and the expansion of the expansion tubes. The thermal expansion of the interconnected inner casings starts from a fixed point arranged on the outer casing of the low-pressure turbine stage furthest upstream. This starting point of the thermal expansions of the inner casing differs from the starting point of the thermal expansions of the rotor, that is defined in a bearing lying further upstream. The expansion tubes are connected in each case via compensators to corresponding outer casings of the low-pressure turbine stages, so that the absolute expansion of the system from the inner casing and coupling rods must be taken by the compensators. To achieve a considerable constancy between the expansion of the turbine rotor and the system consisting of inner casings and connecting rods, the steam is to be applied to the expansion tubes in a preset manner. This steam must either be taken from the steam process or provided separately. It also requires a control and monitoring system by means of which the steam necessary to compensate for the axial play is applied to the expansion tubes in each case depending on the operating state of the steam turbines.
DE 196 29 933 C1 discloses a turbine system with a thrust element, as well as a thrust element. The turbine system has at least two turbine stages, each of which has a turbine rotor extending along a main axis and an inner casing housing the stationary blades. One inner casing can be displaced in the axial direction, with a thrust element that can be thermally expanded being used for an axial displacement. This has a first expansion component and a second expansion component that are connected together by means of a connecting component. This connecting component effects, mechanically and/or hydraulically, an axial displacement of the second expansion component that is greater than a thermal expansion and/or axial displacement of the first expansion component.